Posted on 12/28/2021 4:43:02 AM PST by M. Dodge Thomas
Current market conditions, political pressures, and environmental compliance burdens have greatly reduced the amount of power that coal-fired plants produce annually. However, the greatest impact on coal-fired plants has been the resurgence of the American natural gas market, thus providing an abundant and cheap source of a cleaner-burning fuel. Couple this with the growing impact of renewable energy resources, such as wind and solar power, and it’s easy to understand why many coal-fired plants are struggling to stay in operation.
The survival of coal-fired power plants demands that managers adapt and reinvent their industry. Units must be able to provide cheap, reliable, baseload power, while also being able to follow the frequent changes in power output caused by intermittent renewable power sources. Improving unit flexibility and optimizing assets are great first steps for coal-fired power producers...
Many coal-fired power plants are being asked to ramp output up and down regularly, and often to levels less than units were originally designed to operate at. Implementing a Unit Flexibility and Asset Optimization program can help plants widen operating windows and hit necessary targets.
(Excerpt) Read more at powermag.com ...
The Cliff's Notes answer: operate as much like natural gas-fired peaker plants as possible.
My guess is that this could extend the economic viability of some facilities out toward the end of the decade, which would help to reduce the economic and social pain of phase-out; another five-ten years of employment would make a LOT of difference to those currently employed in the industry.
What an interesting article you posted for us energy/environmental nerds. I have wondered for some time about the problems coal-powered plants have in meeting the modern demands placed on them by the “green energy” parts of the grid. This is the first time I have ever seen it explained so well. (That even I could understand much of it.)
Thanks for posting this.
Gay State, “scrubbers” are already standard operating equipment. This article discusses this a bit.
BFL
The old attack line on coal plants was ‘acid rain’, or sulfur dioxide. Scrubbers, which I suspect are in use on every US coal plant, took care of that. The latest attack line is on carbon emissions (CO2) and there’s no easy way to cut that down significantly. As it is, today, coal plants emit roughly twice as much CO2 as natural gas, per kwh...and that is a big reason for the move away from coal, with the other being the huge amount of cheap natural gas due to fracking.
Coal also isn’t ideal for backing up solar/wind, as the plants are relatively slow to fire up, unlike gas plants, many of which are basically jet engines. Coal is still better than nukes, which are very, very, slow to fire up...but then, by far, leave the smallest footprint of any type of energy production on the planet (so might as well operate nukes at full power...and so their ‘spin-up’ disadvantage is not nearly as big a deal as coal).
Coal plants, themselves, were never designed for quick spin-ups, because back when adults ran the grid, that wasn’t needed, as gas and oil plants took care of that function. So there probably are ways to greatly improve the spin-up capabilities of coal plants - but will the children permit those modifications, rather than just force them to close down and be dismantled (European approach to coal)?
BOBL,
Deep in the technical article is a detailed discussion of how to deal with the issues arising from being a constant state provider and one that has to spool up from time to time. Pretty interesting reading.
Very good share. The core thing facing coal is not that it is more expansive that Natural Gas, it isn’t and the price per kWh is about even.
What is killing coal is that, because of flexibility, a Natural Gas plant can sell its kilowatts for more than a coal plant can.
True for particulate matter, practical for some low level pollutants like oxides of nitrogen, but not practical for "the" major pollutant...carbon dioxide. Which is why natural gas is replacing coal.
Natgas combustion yields a larger fraction of combustion product as water vapor (H2O)..four times more H2O as CO2. Coal is about 1:1 H2O to CO2.
It’s a false ‘renewables driven’ market from subsidies that do not fully recover the actual cost of the energy.
A friend of mine owns a company that “stores” power to meet surge demands for a few east coast power companies. He uses giant flywheels that rotate at insane speeds in a vacuum while suspended by magnetic fields.
They’re spun up during periods of lower demand and when demand increases they slow the flywheels to generate quick power until the nuclear plants can catch up.
I don’t pretend to understand the nuts and bolts of it. But apparently it works well enough.
L
Scrubbers are expensive and power reducing mechanisms that are costly to maintain. Electrostatic precipitators removed @99% of particulates and did a fine job cheaply. They did not remove SO2 however. While SO2 contributes to acid rain so do volcanoes which exceed man made emissions by a large factor. Nowadays, you’re paying a LOT for a very small difference. Like IC vehicles, they (coal fired power plants) will be priced out of the market by mandates/design.
Yea, you can get energy in the flywheels, but it’s likely no more than a few minutes...which is enough time to spin-up a gas turbine in warm backup, but not enough to get coal moving (as you have to first heat up water).
There seems to be a general consensus among readers that the article is worth the read.
I am going to call the article BS before reading as the excerpt leads one in that direction. Yes I will certainly read the article after my comments, which might lead to more comment.
I’ll read later and see where this goes. In my experience the major power producers have been force to cave to radical environmental activists intent on returning the nation to fifth world status in direct conflict with common sense common knowledge, science, engineering and general sane thinking.
That effort has resulted in a very short period of time the shutdown and destruction of gigawatts of coal fired baseload energy production nationwide. There is a price to pay for such abject stupidity and we are enjoying the shrinking difference between what we need 24 seven, three sixty five, maintenance of what it takes for a proper power grid.
Along with the destruction of coal fired energy is the destruction of coal business effecting producer States as well with reduced tax income necessary for their support. With the death or reduction of the coal industry, comes the elevation of natural gas and propane as fuel substitutes.
Natural gas and propane are both volatile price wise in comparison to abundant coal. In addition they both need the competition from coal to remain less volatile and competitive. All base load power needs to be available 24 seven 365. If it is not, one cannot have a viable power grid.
Wind and solar are not dependable 24 seven 365. Thus coal and gas fired energy must be available to meet demand at all times of the day. It is not within the Constitutional purview of Government to tell the power producers with their knowledge how or what should be used to produce power for public use. It is a market that should be allowed to grow or shrink based on usage by the general public.
Just my educated opinion.
Well, it is race; managers in natural gas fired stations are doing the same thing, trying to make their units more flexible to ramp up/down quicker and to be able to operate at lower minimum power then initially designed for.
Few years back, I visited a natural gas power station in UK, one of their unit was on maintenance. Power station main engineer explained they were installing a retrofit that would lower their minimum output. This would allow them to lose less money during the night when prices were lower than their operating cost, but being kept ON was very important because they would be in the market during early morning hours and making their money when prices were high.
They did not want to be switched off during the night, because the cost of re-starting was relatively high, the station is burning fuel on restart without generating electricity, and there was no guarantee that other power plants already ON would not pick up all the necessary power increase in the morning, leaving this power plant offline for entire day…
What bothers me on the greenies negative ideas on coal and nuclear electric power generation is their policies on shutting down working nuclear and coal generating plants long before the useful life of the facilities is over.
Doing that, you lose the value of the investment that would have produced value for a lot of years to come. Even subtracting the day-to-day maintenance and coal cost, there is unrealized value. Plus, with the coal and nuclear plants closed, you have to spend new money to replace them with windmills and solar panels which seem to have useful lives not as long as advertised.
Given that the authors of the articles are taking on subject matter addressed by ‘books of information’ and condensing it down to something suitably sized for a publication like Power, these certainly are very good and well worth the read. Several months ago, there was an article posted on FR about the impact that industrial wind turbines (IWT) and solar had on the grid and many of the issues raised were quite similar as outlined in these articles.
Just as an overview comment, what is entitled “Unit Flexibility and Asset Optimization….” is a euphemism for “Steps that Help Mitigate the Damage done by IWTs and Solar….” These articles are taking it as a given that wind/solar are a ‘fact of life / here to stay’ and for coal-fired power units, what do they have to do to accommodate this. This certainly is a pragmatic approach… and as an aside, the issues are not too much different for natural gas fired boilers. However, stepping back from this further means addressing some very thorny high level questions and these are where the rubber really hits the road…. What is the ‘net electrical contribution’ of wind and solar? What is the net benefit from wind and solar? What is the complete cost of trying to incorporate wind and solar on to the grid? What is the impact of the intermittent electrical supply (wind and solar) doing to the long term reliability of the grid and the traditional electrical generators?
There is so much to address with questions like these but suffice it to say that it goes way beyond simply looking at a boiler unit that was designed for (and likes to run best at) 100% load but can run as low as a 50% turndown….. and then figuring out what electro/mechanical changes can be made to it to get it to run down as to 20%. The Power articles touch on many of the issues that occur when cycling coal-fired units in ways that were never part of the equation but there is so much more… Here are just two issues that come to mind:
- I’ve attended numerous power generation conferences and several years ago, the flag was being waved on what would be the impact of the constant cycling of coal fired plants… the article touches on issues of thermal cycling (thermal fatigue), metallurgical fatigue, corrosion due to condensation, impact on the pollution control systems etc. All of these are in some way going to deeply cut into the life of a coal fired unit and it isn’t just a matter of more frequent component replacements. Who bears this cost?… it certainly won’t be the IWT and solar operators. This is something that got pushed on to existing coal-fired power plants that they never asked for....
- One of the big issues that does not seem to be discussed all that often is the fact that many of the natural gas units that have gone up are simple (open loop) cycle as opposed to combined cycle. This is only being done so that the units can accommodate the rapid ups and downs of IWTs and solar….combined cycle can’t increase/decrease nearly as quickly. This is not a small insignificant point…. to generalize in the interest of brevity, the efficiency of a simple cycle gas unit is say in the 40% range while a combined cycle is in the 60% range. Think about how much more electricity could be generated for the same amount of natural gas if only the combined cycle gas turbines were used. Then give some thought to how much of a reduction there would be to the cycling requirements to existing coal (and natural gas) units if the IWTs and solar didn’t get priority to the grid…. Oh wait, that would mean a whole lot less IWT and solar for the same amount of electricity...
And so it goes. There are lots of impacts to the grid that have been wrought by IWT and solar and almost none of them improves matters.
In my experience the major power producers have been force to cave to radical environmental activists...
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Totally... Saw your post after I put mine up. Would just add that the activists have managed to convince suburbia that wind and solar are green without understanding a wit of the big picture and ripple effect of the implications. Then those folks got clueless politicians involved and the rest is history....
France has load followed with their 75% of the power base miles for decades This is with gen II plants even. Gen III+ can all maneuver to load follow and nearly every one can and is equipped with turbine bypass condensers which can take 100% load in bypass mode allowing for rapid ramp down from 100% to any arbitrary low power level in minutes if they reactor is run in bypass mode it also can ramp back up as fast as the turbines can take steam. Actually maneuvering the reactor output gen III+ can do 10% rates changes per minute that’s only 8 minute from 20% to 100% in a ramp up, ramping down is done much faster via steam bypass.
https://www.powermag.com/flexible-operation-of-nuclear-power-plants-ramps-up/
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